This paper studies the optimization of micro turbine application to meet the electrical, heating and cooling loads of a building by energy, economics and environmental analysis. In this study following three cases are considered: 1: A simple micro gas turbine to meet the electrical power of the building. 2: A simple micro gas turbine to meet the electrical power of the building as well as the power required by heat pump and mechanical refrigerator needed for heating, cooling and domestic hot water (DHW) systems. 3: A CHP micro gas turbine to meet the electrical power of the building as well as part of the power required by heat pump and mechanical refrigerator needed for heating, cooling and DHW systems. The remaining part of the power for heat pump and mechanical refrigerator is provided by the exhaust gases. The research shows that the initial investment is a considerable portion of electricity cost. For an annual interest rate of 10% this portion ranges from 31 to 40% depending on system design configurations, and the lower interest rates results in the smaller portions. it is also concluded that the number of turbine units and electricity cost are highly depended on electricity consumption management. (C) 2009 Elsevier B.V. All rights reserved.